With the widespread recognition of a low-carbon economic and a low-carbon development concept in various countries in the world, a large amount of wastewater discharge has become the primary challenge in the textile printing and dyeing industry. China's textile industry is facing an extremely grim prospect in the low carbon economy. According to incomplete statistics, the total amount of wastewater discharged by printing and dyeing enterprises in China reaches 3 to 4 million tons per day, COD and BOD are as high as 2000-3000 mg/L, residual dyes, heavy metals, sulfur compounds and various kinds of non-biodegradable organic additives in wastewater are difficult to be treated effectively by coagulation, filtration, adsorption and other methods, and therefore the wastewater discharged by printing and dyeing enterprises is one of industrial wastewaters which are most difficult to treat.
At the same time, statistics from China Printing and Dyeing Industry Association show that the annual water consumption of the printing and dyeing industry in China reaches 9.548 billion tons, the fresh water consumption takes the second place among various industries in the country, wherein the printing and dyeing water accounts for 80%. The total amount of printing and dyeing wastewater discharged is ranked sixth in the total emissions of various industrial sectors across the country. High dependence on water resources and high energy consumption, high emissions and other issues have seriously hampered the sustainable development of the textile printing and dyeing industry. In particular, “Carbon Tariff” implemented by developed countries have further exacerbated the impact on the textile printing and dyeing industry, which is at the low end of the textile supply chain in China. Therefore, as an important industry in the low-carbon development plan in China, the textile printing and dyeing industry must speed up its integration with the “low-carbon era.” The implementation of clean production of the printing and dyeing process is the only way for the sustainable development of the industry as a whole. The development of the less-water, energy-saving and pollution-free dyeing technology has become an urgent need at home and abroad.
At present, the supercritical CO2 fluid dyeing technology as a clean dyeing technology has made progress at home and abroad; wherein, the use of disperse dyes for supercritical CO2 fluid dyeing of chemical fiber bulk fiber has entered the stage of industrial production, and has the advantages of small batches and multiple varieties. However, batch dyeing of fabric supercritical CO2 fluid still has the problems of long dyeing time and low dyeing efficiency. In addition, supercritical CO2 fluid dyeing of a rope fabric can also cause the problems of dyeing spots and fabric creases. The above problems have become the bottleneck restricting the industrialization application of batch supercritical CO2 fluid dyeing and finishing of fabrics.